The power unit in the Russian SUV UAZ Patriot is the ZMZ-409 engine. Like any other engine, it requires the presence of a cooling system, and it must function properly and continuously while the engine is running. If this condition is not met, the engine will experience overheating and subsequent failure.
In order to eliminate such negative consequences, the UAZ Patriot system requires continuous temperature control. If the temperature level displayed by a special sensor exceeds 90 degrees, then the driver should immediately stop the engine and find out the reasons for the violation of the regulatory regime. It will probably need replacement.
In the cooling circuit of the UAZ Patriot engine, a very important component is the thermostat for the 409 engine. It is this detail that our material today is devoted to. Here we will look at what the purpose of the thermostat on a 409 engine is and how to replace it if it begins to show signs of malfunction.
The purpose of the thermostat in this car
The device is designed to redistribute flows during coolant circulation between the so-called small and large circles. In the first case, the thermostat on the 409 engine closes the circuit in a small circle when the liquid circulates in the cooling jacket and radiator of the UAZ Patriot heating system. This situation occurs when the engine warms up to operating temperature. When a certain temperature limit is reached, the valve inside the thermostat begins to move, thereby opening the path of liquid in a large circle. In this case, the coolant circulates through the main radiator, which, with the help of a fan, removes excess heat. If faulty, replacement is required.
Replacing the thermostat on a UAZ
The thermostat is an important part of the engine cooling system. Since UAZ SUVs are quite heavy frame vehicles, their engines are almost always loaded, hence the risk of overheating. It is important that the cooling system works perfectly.
The thermostat is designed to distribute coolant (antifreeze or antifreeze) over the so-called cooling “circuits”. There are only two of them: a small circuit and a large circuit. From the moment the car is started until the liquid warms up to a certain temperature (80-90 degrees), a small circle operates. The large circle turns on after this temperature, this is the “opening” temperature of the thermostat. In a large circle, the coolant flows through a large cooling radiator, which is located in the front of the car.
Maybe repairs are possible? Unfortunately no, definitely change them, since they cannot be repaired. There may be several reasons why you may need to replace the UAZ thermostat:
- It may get stuck in the closed position when only the small circuit is operating.
- In the open position, when a large circle is running, the machine takes a very long time to warm up.
- An intermediate option when the thermostat is stuck in the half-open or half-closed position.
- A problem is possible, as a result of which the valve opening temperature may decrease by several degrees, which again will lead to “underheating” of the machine to operating temperature in winter.
This is how they usually check the actual valve opening temperature.
From the factory, UAZs are equipped with thermostats whose opening temperature is too low (82-84 degrees). Since there is a belt-driven fan installed from the factory to cool the engine, it always runs when the engine is running. Because of this, in winter it is difficult to warm up the car completely, so it is necessary to set the valve to a higher temperature. In summer the situation is reversed - it is necessary to install a valve with a lower opening temperature. The problem can be radically solved only by replacing the original fan with an electric one; it is even better to install 2 electric fans at once.
There were a lot of engines installed on UAZ, so the location of the thermostat may be slightly different for everyone. For example, on engines ZMZ 402 (UAZ loaf), 410, 417 it is located almost at the highest point, so to replace it you will have to drain just a little bit of liquid.
But on the UAZ “Patriot” and on the Hunter it is located in a slightly different place, you can see this for yourself by watching a video about replacing the thermostat on a UAZ Patriot.
After replacement, it is necessary to remove air from the system; after adding antifreeze to the required level, you need to start the engine and rev it up a little, because the higher the speed, the stronger the pump pumps liquid through the system. Prepare for the fact that the antifreeze will gradually disappear while the engine is running; make sure that its level does not go below about 0, otherwise there is a risk of air getting into the cooling system.
It’s up to you to install an original spare part or its equivalent, but if you decide to install, for example, a “TAMA” thermostat with an opening temperature of 88 degrees, you will most likely have to sharpen it in a circle, otherwise it may not fit into the seat, all this is shown in the video .
So, replacing the thermostat on a UAZ yourself, this can be said to be the “ABC” (UAZBUKA) for any driver, because problems with cooling can happen on the road, for example, on a long trip, when there is no one around, it is important to know and be able to quickly eliminate them.
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Features of the thermostat in UAZ Patriot
With operating experience, UAZ Patriot owners noticed that the standard thermostat for the 409 engine has a short service life. The main reason for incorrect operation is that the valve inside the thermostat begins to open earlier than the temperature level corresponding to the operating mode of the UAZ Patriot engine is reached. If the factory calculates that the thermostat should open when the temperature reaches 87 degrees, which is actually the operating mode, then the valve often begins to open already at 76-78 degrees. What does this situation lead to? Firstly, warming up the engine takes significantly longer, and secondly, in cold weather it becomes problematic to fill the cabin with hot air.
The thermostat on the 409 engine that has shown to be faulty must be unconditionally replaced. Here the owner is advised not to bother changing the unit to a standard analogue, because the risk of changing an awl for soap is very high. You can act more rationally and install a higher quality product, for example, “TAMA” from Pajero.
Another well-known option is “Pekar”, but its operating temperature is 80 degrees, but in reality it barely reaches 75 degrees. A characteristic feature of “TAMA” is the fact that during operation the refrigerant temperature rises by 1 degree. That is, the operating temperature level here is 88 degrees, and when the standard product is functioning - 87 o.
For the ZMZ-409 motor, TAMA is installed without any need for modification, since the geometric parameters of both parts are identical. But this is true for trim levels equipped with Euro 3 or Euro 4 systems.
What if the UAZ Patriot is equipped with Euro 2? In this case, installation is also possible, but with the condition that the thermostat plate is replaced with an analogue from a standard product. This is necessary for the valve to completely close the channel to the pump. It is also possible to “adjust” the existing plate from TAMA to identical dimensions with the standard device.
By performing such a replacement, the owner of the UAZ Patriot will provide a significantly longer thermostat resource, and the engine will begin to warm up with noticeable efficiency.
Now let's move on to considering situations in which the thermostat requires replacement. Let’s also figure out how to identify the presence of a malfunction?
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What is a thermostat for?
On any engine, the thermostat performs the same task. It consists in regulating the temperature of the coolant. Due to the circulation of antifreeze in the cooling system, warming up of the engine when starting it is accelerated and the required temperature is maintained.
When the unit starts, the thermostat blocks the flow of antifreeze until the engine warms up to the desired temperature level. When the unit is cold, liquid does not pass through it, which means the unit heats up much faster. This process takes literally a couple of minutes. Coolant begins to enter the system of the unit only when it warms up to 87 degrees, this is the case with UAZ Patriot cars.
Then the thermostat opens and antifreeze begins to flow into the engine. Such a cooling system device has two advantages:
- reduction of engine wear;
- reducing the amount of harmful exhaust gases.
Despite the fact that only high-quality materials with an increased service life are used in the manufacture of thermostat parts, the mechanism operates under extremely aggressive conditions, so sometimes it can fail. The risk increases at high air temperatures during the warm season.
Disadvantages of the mechanism
Important! The Ulyanovsk thermostat for the Patriot class Euro-3 and Euro-4 has an extremely short service life due to the technical features of its design.
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The problem of a breakdown of the cooling system is quite typical for the UAZ Patriot jeep. A factory part fails at the most inopportune time. The Potomac leads to the following consequences:
- The thermostat should open when the temperature reaches 87 degrees. If it is faulty, its operating temperature drops to about 70 degrees, as a result the unit begins to operate at the wrong temperature, its service life is reduced, and the stove stops supplying fairly warm air into the cabin for proper heating.
- The engine will overheat too quickly, which can lead to serious damage.
The consequences of a thermostat malfunction will depend on the nature of its failure. We will try to understand further the nuances of the failure of this important mechanism.
Thermostat malfunctions in Patriot
Among the main signs is a disrupted operating temperature. This can be observed from the temperature sensor, when its needle for a long time cannot approach the operating threshold (87 degrees), but stops at a significantly lower reading.
Sometimes the valve gets stuck in the closed position. Here everything will happen the other way around, that is, the temperature will continue to rise far beyond the operating limit (87 degrees). There is a risk of motor overheating. In addition to the thermostat, in such a situation the driver can be “let down” by the fan, which may refuse to start at the required moment. You should also check the refrigerant level in the tank. If the fan is working and the level is normal, then you can now safely “blame” the thermostat on the 409 engine.
How to check if the thermostat is working correctly? The product will need to be dismantled (discussed below). Place the removed part in a container with water. Heat to a boil and watch the valve. If it refuses to move, then we determine the output and build the thermostat.
So, the product is considered operational if:
- the valve opening temperature is 78 degrees;
- temperature when fully opened is 87 degrees.
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UAZ vehicles with a UMZ-417 engine use a liquid, closed cooling system, with forced circulation of coolant by a centrifugal pump of the cooling system. Depending on the configuration, the UAZ-3151 and some other models can be equipped with a pre-heater integrated into the cooling system. Low-freezing liquid is used as a coolant.
For normal operation of the UMZ-417 engine, the coolant temperature must be maintained within 70-90 degrees. This temperature is achieved using an automatically operating thermostat, which regulates the amount of liquid passing through the radiator and blinds, with the help of which they regulate the amount of air cooling the radiator.
Monitoring the coolant temperature in the UMZ-417 cooling system.
To monitor the coolant temperature, there is an electric indicator on the instrument panel, the sensor of which is screwed into the cavity of the water pump bracket. In addition, overheating of the coolant is indicated by a warning lamp with a red filter installed on the instrument panel and connected by an electrical wire to a sensor screwed into the upper radiator tank.
The control lamp lights up when the coolant reaches a temperature of 92-98 degrees. When the warning light comes on, the radiator shutters must be opened. The causes of overheating may be:
- low fluid level in the radiator - low fan belt tension - driving with the blinds closed or the insulating cover valve closed
Maintenance of the UMZ-417 engine cooling system.
The coolant level in the expansion tank is checked on a cold engine; it should be 30-40 mm above the “Min” mark. When the level of low-freezing liquid decreases as a result of its boiling, it is necessary to add clean water to the cooling system, since water evaporates from the liquid first, due to the fact that the boiling point of water is much lower than ethylene glycol. If the liquid level decreases as a result of leakage, it is necessary to add low-freezing liquid after eliminating the cause of the leakage.
The low-freezing liquid in the UMZ-417 engine cooling system is replaced every 2 years or after 60,000 kilometers. Before adding fresh fluid, it is recommended to flush the cooling system with clean water. Liquid is drained from the cooling system through two taps. One is located on the lower radiator tank, the other on the cylinder block, or, if a pre-heater is installed on the UAZ, then on its boiler.
Cooling system water pump maintenance.
Centrifugal type, driven by a V-belt from the crankshaft pulley. The pump design uses a ball-roller bearing, manufactured integrally with the pump shaft. The bearing has special seals that ensure preservation of the lubricant incorporated during manufacture. The bearing does not require additional lubrication during operation. Coolant leakage through the inspection hole indicates a faulty seal.
Some UAZ vehicles with UMZ-4178 and UMZ-4179 engines can be equipped with a water pump whose design uses ball bearings. In such pumps, the cavity is sealed using a rubber cuff, which is tightly pressed by a spring to the sealing washer and the pump shaft.
The bearings of such a water pump are lubricated after one regular maintenance with Litol-24 type grease through a grease nipple until the grease comes out of the control hole. Excess grease must be removed as it may get on the fan belt.
Tension of the fan belt of the UMZ-417 engine cooling system.
It is checked by pressing it between the pulleys of the water pump and the generator with a force of 39 N. The belt deflection should be within 8-14 mm. To adjust the tension belt, you need to loosen the generator mounting bolts, move it in the required direction, tighten the bolts and check the belt tension again.
Checking the operation of the cooling system thermostat.
A locking-type thermostat with a solid filler is located in the outlet pipe located on the bracket of the cooling system pump, and operates as a result of the movement of the rod in the thermostat cylinder. The thermostat valve begins to open at a coolant temperature of 69-72 degrees and fully opens at a temperature of 81-85 degrees. The thermostat, by turning the radiator on or off, automatically maintains the required temperature of the coolant in the engine.
Operating the UMZ-417 engine without a thermostat is unacceptable, since when it is removed, the main flow of coolant will circulate through a small circle of the cooling system, bypassing the radiator, which will lead to overheating of the engine.
The operation of the thermostat is checked simultaneously with flushing the cooling system, as well as during systematic overheating of the engine, and when the power and ignition systems are working properly. To check, the thermostat and thermometer are placed in a vessel with water heated to a temperature of 90-100 degrees. Then, as the water gradually cools, the temperature at which the thermostat valve begins and ends is controlled. The faulty thermostat is replaced with a new one.
Replacing the thermostat in a UAZ Patriot
The replacement is performed on a cooled motor and has the following sequence of manipulations.
- Drain the refrigerant. We attract a suitable container.
- Unscrew the fasteners of the hydraulic steering pump. We move the pump unit to the side.
- On the supply hose from the radiator to the UAZ Patriot thermostat housing, loosen the clamp and move it.
- Disconnect the connectors with wires from the plugs on the case. Replacement continues.
- We also loosen and move the upper clamp present on the hose from the body to the pump, after which we tighten the pipe itself.
- We unscrew the screws securing the housing, having first loosened the fastening of the cover.
- Remove the housing, and then completely unscrew and remove the cover.
- We take out the thermostat.
Before installing the product, install a new gasket. Replacement is complete.
Let's sum it up
As it turns out, the thermostat on a 409 engine is a very important component in the cooling circuit. On the ZMZ-409 UAZ Patriot engine, replacing it turned out to be a simple procedure. The manufacturer recommends replacing a worn-out element with a new factory-made analogue, however, as we understand, this product is not famous for its service life and correct operation. Here it is better to lean towards choosing a higher quality analogue, which we mentioned in this article. After assembling the circuit and starting the engine, we check the system for refrigerant leaks.
What to do if the thermostat fails
If a thermos on a UAZ Patriot breaks down, there are two options for fixing this problem:
- Buy an original part from a domestic manufacturer.
- Buy a foreign analogue of much better quality, for example -.
As practice shows, imported mechanisms last much longer and perform well in a wide variety of operating conditions. If you decide to install a Tama thermostat on the Patriot engine, you should take into account that its operating temperature is 88 degrees. This is a minor difference compared to a thermostat from a Russian manufacturer. In addition, the Japanese part has similar parameters to the domestic ones, which means there will be no problems with its installation.
